Pressure-sensitive adhesives in tape or sheet form are used in various applications. Damping adhesives for vibration insulation are among them. Adhesives of this type have been widely applied to automobile parts, various appliances, etc. as a means for reducing vibration or noise, and many studies have been made on temperature characteristics of their vibration-damping properties for making the best use thereof at the working temperature.
Requirements for the vibration-damping adhesives have been increasing year by year. For use in appliances, in particular, demands for durability and reliability in high working temperatures have become severer. However, most of the pressure-sensitive adhesives of this type, which mainly comprise high polymeric materials, undergo decomposition or oxidation on long-term use at high temperatures, causing various problems. For example, decomposition or oxidation of the high polymeric material leads to hardening or oozing of the adhesive and generates decomposition gases. This results in a reduction of vibration-damping properties and pollution of the surrounding air. The currently available vibration-damping pressure-sensitive adhesives are unsatisfactory from this point of view.